"Apple pieces are promising carriers for probiotic bacteria and may be used in the production of probiotic fermented milk and/or other food products, as well as in the prolongation of their shelf-life," wrote lead author Yiannis Kourkoutas from the University of Patras.
"Freeze-dried apple-supported L. casei biocatalyst could be added to various solid foods (breakfast cereals, used in baking, etc.) to provide probiotic properties."Most foods containing probiotic bacteria are found in the refrigerated section of supermarkets as the bacteria is destroyed by heat and other processing conditions.
This has given the dairy sector, already used to handling live bacteria for the manufacture of yoghurt, a major advantage in probiotic foods - probiotic drinking yoghurts are currently the fastest growing dairy product in Europe.
However major food companies have been investigating probiotic use in other food categories, indicating that this is a very relevant area for the health foods industry at present. The first cereals, bars and chocolates and cookies with probiotics have started to appear on the market.
"Production of probiotic foods containing specific probiotic strains at suitable levels of viable cells during their self-life is a technological challenge," explained Kourkoutas.
The supported probiotic was prepared by adding the apple pieces to Lactobaccillus casei cell culture and allowed to ferment overnight. It was then decanted, washed and was then ready for use.
Kourkoutas and his co-workers report that the apple-supported L. casei was suitable for probiotic fermented milk production, and that, even after 129 days of storage, the probiotic cells were still viable.
"L. casei cells immobilized on apple pieces survived for extended storage time periods and were adapted to the acidic environment, which usually has an inhibitory effect on cells survival," said the researchers.
"The improved aroma of the fermented milk encourages further research on this subject," said the researchers.
The fruity aroma was also still evident after 129 days of storage, they said.
"Taking into account that probiotic properties are obtained when a product contains adequate amount of live bacteria at least 107 cfu/g, it seems that cell immobilization on apple pieces may play a positive role in cell survival," they concluded.
Increasing research has focused on expanding protecting probiotics during processing and expanding the food categories available to prebiotics. Such an avenue of research has led companies like Cell Biotech from Korea using a dual-coating to protect probiotics against oxygen, acid, moisture and high temperatures for use in emerging new product categories such as breakfast cereals and smoothies.
Recently, NutraIngredients.com reported on innovative research from the Technical Research Centre of Finland (VTT) investigated the capabilities of various prebiotic fibres to protect the stability and viability of probiotic Lactobacillus rhamnosus strains during freeze-drying, storage in freeze-dried form and after formulation into apple juice and chocolate-coated breakfast cereals.
Source: LWT- Food Science and Technology Volume 39, Issue 9, Pages 980-986 "Apple pieces as immobilization support of various microorganisms" Authors: Y. Kourkoutas M. Kanellaki and A.A. Koutinas